1. Field of the Invention
This invention relates generally to reducing the amount of pollutants expelled by a vehicle.
2. Description of the Related Art
It is well-known that vehicles powered by an internal combustion engine generate pollutants that are expelled through its exhaust system. It is useful to decrease the amount of pollutants expelled by the vehicle because of the negative environmental and health effects associated with them. The pollutants can be of many different types, such as gaseous carbon monoxide, hydrocarbons and nitrogen oxides, as well as solid particulate matter. Carbon monoxide is known to be a poisonous gas and hydrocarbons are known to include carcinogens, as well as photochemically active chemicals that cause the formation of ozone and smog. Further, nitrogen oxides are known to cause the formation of smog and acid rain. Solid particulate matter generally includes soot and hydrocarbons from uncombusted fuel, which can damage the lungs when inhaled.
Most vehicles include a catalytic converter to reduce the amount of pollutants expelled. The catalytic converter is included with the vehicle exhaust system and converts pollutants generated by the engine to less harmful chemical species. For example, the catalytic converter is effective at converting the pollutants to carbon dioxide, water and nitrogen. However, it is desirable to further reduce the amount of pollutants expelled by the vehicle.